CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-36187, filed on Feb. 22, 2012; the entire contents of which are incorporated herein by reference.
FIELD
Embodiments described herein relate generally to a semiconductor device and a manufacturing method of a semiconductor device.
BACKGROUND
The array pitch of contacts of wires becomes small with the scaling of a line and space of the wires, therefore, it has becomes difficult to lay out the contacts. If the contacts are arranged offset from each other to lay out the contacts, the chip size increases by the amount of offset of the contacts.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view illustrating a schematic configuration of a contact region of a semiconductor device according to a first embodiment;
FIG. 2A to FIG. 2E are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to a second embodiment;
FIG. 3A is a plan view illustrating a manufacturing method of a contact region of a semiconductor device according to a third embodiment and FIG. 3B is a cross-sectional view cut along line A-A in FIG. 3A;
FIG. 4A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 4B is a cross-sectional view cut along line A-A in FIG. 4A;
FIG. 5A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 5B is a cross-sectional view cut along line A-A in FIG. 5A;
FIG. 6A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 6B is a cross-sectional view cut along line A-A in FIG. 6A;
FIG. 7A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 7B is a cross-sectional view cut along line A-A in FIG. 7A;
FIG. 8A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 8B is a cross-sectional view cut along line A-A in FIG. 8A;
FIG. 9A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 9B is a cross-sectional view cut along line A-A in FIG. 9A;
FIG. 10A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 10B is a cross-sectional view cut along line A-A in FIG. 10A;
FIG. 11A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 11B is a cross-sectional view cut along line A-A in FIG. 11A;
FIG. 12A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 12B is a cross-sectional view cut along line A-A in FIG. 12A;
FIG. 13A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment and FIG. 13B is a cross-sectional view cut along line A-A in FIG. 13A;
FIG. 14A is a plan view illustrating the manufacturing method of the contact region of the semiconductor device according to the third embodiment, FIG. 14B is a cross-sectional view cut along line A-A in FIG. 14A when contact holes are vertically processed, and FIG. 14C is a cross-sectional view cut along line A-A in FIG. 14A when contact holes are tapered;
FIG. 15A is a plan view illustrating a manufacturing method of a contact region of a semiconductor device according to a fourth embodiment and FIG. 15B is a cross-sectional view cut along line A-A in FIG. 15A;
FIG. 16A is a plan view illustrating a manufacturing method of the contact region of the semiconductor device according to the fourth embodiment, FIG. 16B is a cross-sectional view cut along line A-A in FIG. 16A, and FIG. 16C is a cross-sectional view illustrating a configuration in which upper layer wires are formed on contacts in FIG. 16B;
FIG. 17A to FIG. 17F are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to a fifth embodiment;
FIG. 18A to FIG. 18F are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to a sixth embodiment;
FIG. 19A to FIG. 19D are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to a seventh embodiment; and
FIG. 20A to FIG. 20D are plan views illustrating the manufacturing method of the contact region of the semiconductor device according to the seventh embodiment.
DETAILED DESCRIPTION
In general, according to one embodiment, a plurality of wires, a plurality of first contacts, and a plurality of second contacts are included. The wires are arranged in parallel at a predetermined pitch. The first contacts are each connected to an odd-numbered wire among the wires and are arranged in parallel in an orthogonal direction with respect to a wiring direction of the wires. The second contacts are each connected to an even-numbered wire among the wires and are arranged in parallel in an orthogonal direction with respect to the wiring direction of the wires in such a way as to be offset from the first contacts in the wiring direction of the wires. The first contacts are offset from the second contacts by a pitch of the wires in an orthogonal direction with respect to the wiring direction of the wires.
A semiconductor device and a manufacturing method of the semiconductor device according to the embodiments will be explained below with reference to the drawings. The present invention is not limited to these embodiments.
First Embodiment
FIG. 1 is a plan view illustrating a schematic configuration of a contact region of a semiconductor device according to the first embodiment. A NAND flash memory is applied as an example of the semiconductor device.
In FIG. 1, bit lines BL1 to BL8 are arranged in parallel at a wiring pitch PH in an orthogonal direction with respect to a wiring direction thereof. The wiring pitch PH of the bit lines BL1 to BL8 can be made to correspond to a minimum pitch of a line and space in a semiconductor integrated circuit. This wiring pitch PH can satisfy the relationship PH<0.25*λ/NA, where λ is an exposure wavelength in lithography and NA is a numerical aperture in a projection optical system. Moreover, a width HP of each of the bit lines BL1 to BL8 can be made to correspond to ½ of a minimum pitch in a semiconductor integrated circuit.
The bit lines BL1 to BL8 are provided with a contact region CR and bit contacts CB and CB′ are formed in the contact region CR. The bit contacts CB′ are connected to odd-numbered bit lines among the bit lines BL1 to BL8 and the bit contacts CB are connected to even-numbered bit lines among the bit lines BL1 to BL8. The bit contacts CB′ are arranged in parallel in an orthogonal direction with respect to the wiring direction of the bit lines BL1 to BL8 and the bit contacts CB are arranged in parallel in an orthogonal direction with respect to the wiring direction of the bit lines BL1 to BL8 in such a way as to be offset from the bit contacts CB′ in the wiring direction of the bit lines BL1 to BL8. The bit contacts CB are offset from the bit contacts CB′ by the wiring pitch PH in an orthogonal direction with respect to the wiring direction of the bit lines BL1 to BL8. In other words, an interval DA between the bit contacts CB and CB′ in an orthogonal direction with respect to the wiring direction of the, bit lines BL1 to BL8 is equal to the wiring pitch PH. At this time, the accuracy of the interval DA between the bit contacts CB and CB′ is equal to the accuracy of the wiring pitch PH.
Moreover, word lines WL1, WL2, WL1′, and WL2′ and select gate lines SGD and SGD′ are arranged in parallel in an orthogonal direction with respect to the wiring direction of the bit lines BL1 to BL8. The contact region CR is arranged between the select gate lines SGD and SGD′. The word lines WL1 and WL2 are arranged on the select gate line SGD side and the word lines WL1′ and WL2′ are arranged on the select gate line SGD′ side.
The lower ends of the bit contacts CB and CB′ can be connected to a high-concentration impurity diffusion layer formed between the select gate lines SGD and SGD′ in active areas isolated from each other by a trench.
The bit contacts CB′ are connected to odd-numbered bit lines among the bit lines BL1 to BL8, the bit contacts CB are connected to even-numbered bit lines among the bit lines BL1 to BL8, and the bit contacts CB are arranged offset from the bit contacts CB′ in the wiring direction of the bit lines BL1 to BL8, therefore, even when the wiring pitch PH of the bit lines BL1 to BL8 corresponds to a minimum pitch by optical lithography, a short circuit between the bit contacts CB and CB′ can be prevented while suppressing an increase in a width DY of the contact region CR.
Second Embodiment
FIG. 2A to FIG. 2E are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to the second embodiment.
In FIG. 2A, mask patterns 1 are formed on a reticle 7. A plurality of the mask patterns 1 having a linear shape is formed in parallel in an orthogonal direction with respect to a wiring direction DH in such a way as to be offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. The wiring pitch PH can be made to correspond to a minimum pitch of a line and space in a semiconductor integrated circuit. This wiring pitch PH can satisfy the relationship PH<0.25*λ/NA, where λ is an exposure wavelength in lithography and NA is a numerical aperture in a projection optical system. At this time, the width of the mask pattern 1 can be set to 2 PH. Moreover, the interval between the mask patterns 1 can be set to 2 PH.
Then, as shown in FIG. 2B, core patterns 2 onto which the mask patterns 1 are transferred are formed on a processing target layer 8 by using a method such as ArF immersion exposure. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the core patterns 2. The processing target layer 8 may be a semiconductor substrate, a dielectric layer formed on the semiconductor substrate, or the like, and is not specifically limited.
Next, as shown in FIG. 2C, the core patterns 2 are slimmed by a method, such as isotropic etching, to thin the line width of the core patterns 2. Then, for example, a sidewall material having a high selectivity with respect to the core patterns 2 is deposited on the whole surface of the processing target layer 8 including the sidewalls of the core patterns 2 by a method, such as the CVD. As the sidewall material having a high selectivity with respect to the core patterns 2, for example, when the core pattern 2 is formed of a BSG film, a silicon nitride film can be used. Then, the processing target layer 8 is exposed while leaving the sidewall material on the sidewalls of the core patterns 2 by performing anisotropic etching on the sidewall material, thereby forming sidewall patterns 3 on the sidewalls of the core patterns 2. At this time, the sidewall pattern 3 is offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Next, as shown in FIG. 2D, the core patterns 2 are removed from over the processing target layer 8 while leaving the sidewall patterns 3 on the processing target layer 8. Next, mask patterns 4 that cover part of the spaces between the sidewall patterns 3 are formed on the processing target layer 8 by using the photolithography technology and the etching technology, thereby forming openings H11 and H11′ surrounded by the sidewall patterns 3 and the mask patterns 4. At this time, the openings H11 and H11′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings H11′ of the first row are offset from the openings H11 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the mask patterns 4.
Then, openings 5 and 5′ formed by transferring the openings H11 and H11′ are formed in the processing target layer 8 by etching the processing target layer 8 via the openings H11 and H11′. At this time, the openings 5 and 5′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings 5′ of the first row are offset from the openings 5 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Then, as shown in FIG. 2E, the sidewall patterns 3 and the mask patterns 4 are removed from over the processing target layer 8 in which the openings 5 and 5′ are formed. Thus, wires arranged in parallel at the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH can be formed on the openings 5 and 5′ along the wiring direction DH. The width of the wires can be set to ½ of the wiring pitch PH.
The openings 5 and 5′ are formed in the regions partitioned by the sidewall patterns 3, therefore, even when the wiring pitch PH is set equal to or less than the resolution of the lithography, the contacts can be formed in the wires by arranging the openings 5 and 5′ in two rows.
Third Embodiment
FIG. 3A to FIG. 14A are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to the third embodiment, and FIG. 3B to FIG. 13B are cross-sectional views cut along line A-A in. FIG. 3A to FIG. 13A, respectively, FIG. 14B is a cross-sectional view cut along line A-A in FIG. 14A when contact holes are vertically processed, and FIG. 14C is a cross-sectional view cut along line A-A in FIG. 14A when contact holes are tapered.
In FIG. 3A and FIG. 3B, an interlayer dielectric film 12 is formed on an underlying layer 11 and lower layer wires 13 are embedded in the interlayer dielectric film 12. The underlying layer 11 may be a semiconductor substrate, a dielectric layer formed on the semiconductor substrate, or the like, and is not specifically limited. An interlayer dielectric film 14 is formed on the lower layer wires 13 and mask layers 15 and 16 and a core layer 17 are sequentially stacked on the interlayer dielectric film 14. Moreover, the lower layer wires 13 may be active areas isolated by a trench in a NAND flash memory.
Then, mask patterns 18 are formed on the core layer 17 by using a method such as ArF immersion exposure. A plurality of the mask patterns 18 having a linear shape is formed in parallel in an orthogonal direction with respect to the wiring direction DH in such a way as to be offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. A resist material can be used as the material for the mask patterns 18.
Next, as shown in FIG. 4A and FIG. 4B, core patterns 19 onto which the mask patterns 18 are transferred are formed on the mask layer 16 by etching the core layer 17 with the mask patterns 18 as a mask. A hard mask material, such as a BSG film and a silicon nitride film, can be used as the material for the core patterns 19.
Next, as shown in FIG. 5A and FIG. 5B, the core patterns 19 are slimmed by a method, such as isotropic etching, to thin the line width of the core patterns 19.
Next, as shown in FIG. 6A and FIG. 6B, for example, a sidewall material 20 having a high selectivity with respect to the core patterns 19 is deposited on the whole surface of the mask layer 16 including the sidewalls of the core patterns 19 by a method, such as the CVD. As the sidewall material 20 having a high selectivity with respect to the core patterns 19, for example, when the core pattern 19 is formed of a BSG film, a silicon nitride film can be used.
Next, as shown in FIG. 7A and FIG. 7B, the mask layer 16 is exposed while leaving the sidewall material 20 on the sidewalls of the core patterns 19 by performing anisotropic etching on the sidewall material 20, thereby forming sidewall patterns 21 on the sidewalls of the core patterns 19. At this time, the sidewall pattern 21 is offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Next, as shown in FIG. 8A and FIG. 8B, the core patterns 19 are removed from over the mask layer 16 while leaving the sidewall patterns 21 on the mask layer 16.
Next, as shown in FIG. 9A and FIG. 9B, the sidewall patterns 21 are transferred onto the mask layer 16 by etching the mask layer 16 with the sidewall patterns 21 as a mask. A material having a low selectivity with respect to the sidewall patterns 21 can be used as the material for the mask layer 16. For example, when the sidewall pattern 21 is formed of a silicon nitride film, a BSG film can be used as the mask layer 16.
Next, as shown in FIG. 10A and FIG. 10B, a mask layer 22 is formed on the mask layer 15 in such a way that the mask layer 16 onto which the sidewall patterns 21 are transferred is embedded. Furthermore, a mask layer 23 is formed on the mask layer 22. A material having a low selectivity with respect to the mask layer 16 and the mask layer 22 can be used as the material for the mask layer 15. Moreover, a material having a low selectivity with respect to the mask layer 16 can be used as the material for the mask layer 22. For example, when the mask layer 16 is formed of a BSG film, a polycrystalline silicon film can be used as the mask layer 22 and a silicon nitride film can be used as the mask layer 15. Moreover, a resist material can be used as the material for the mask layer 23.
Next, as shown in FIG. 11A and FIG. 11B, the mask layer 23 is patterned in such a way as to expose regions between a stepped portion and both end portions of the mask layer 16 onto which the sidewall patterns 21 are transferred by using the photolithography technology. Then, the mask layer 22 between the mask layers 16 exposed from the mask layer 23 is removed by etching the mask layer 22 via the patterned mask layer 23, thereby forming openings H0 and H0′ surrounded by the patterned mask layers 16 and 22. At this time, the openings H0′ are arranged in parallel in the first row in an orthogonal direction with respect to the wiring direction DH and the openings HO are arranged in parallel in the second row in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings H0′ of the first row are offset from the openings H0 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Next, as shown in FIG. 12A and FIG. 12B, after removing the mask layer 23, the openings H0 and H0′ are transferred onto the mask layer 15 by etching the mask layer 15 via the openings H0 and H0′ surrounded by the mask layers 16 and 22, thereby forming the openings H1 and H1′ in the mask layer 15.
Next, as shown in FIG. 13A and FIG. 13B, the mask layers 16 and 22 are removed from over the mask layer 15 in which the openings H1 and H1′ are formed.
Next, as shown in FIG. 14A and FIG. 14B, the openings H1 and H1′ are transferred onto the interlayer dielectric film 14 by etching the interlayer dielectric film 14 via the openings H1 and H1′ formed in the mask layer 15, thereby forming openings H2 and H2′ in the interlayer dielectric film 14. At this time, the surfaces of the lower layer wires 13 are exposed via the openings H2 and H2′. A material having a low selectivity with respect to the mask layer 15 can be used as the material for the interlayer dielectric film 14. For example, when the mask layer 15 is formed of a silicon nitride film, a silicon oxide film can be used as the interlayer dielectric film 14.
When etching the interlayer dielectric film 14 via the openings H1 and H1′, the bottom portions of the openings H2 and H2′ may be thinned as shown in FIG. 14C by tapering the interlayer dielectric film 14. At this time, the width of the bottom portions of the openings H2 and H2′ can be made equal to the width of the lower layer wires 13.
Fourth Embodiment
FIG. 15A and FIG. 16A are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to the fourth embodiment, FIG. 15B and FIG. 16B are cross-sectional views cut along line A-A in FIG. 15A and FIG. 16A, respectively, and FIG. 16C is a cross-sectional view illustrating a configuration in which upper layer wires are formed on contacts in FIG. 16B.
In FIG. 15A, after the processes in FIG. 13A and FIG. 13B, sidewall patterns 27 are formed on the sidewalls of the openings H1 and H1′ to form openings H3 and H3′ surrounded by the sidewall patterns 27.
Next, as shown in FIG. 16A and FIG. 16B, the openings H3 and H3 are transferred onto the interlayer dielectric film 14 by etching the interlayer dielectric film 14 via the openings H3 and H3 surrounded by the sidewall patterns 27, thereby forming openings H4 and H4′ in the interlayer dielectric film 14. At this time, the width of the openings H4 and H4′ can be made equal to the width of the lower layer wires 13.
Next, as shown in FIG. 16C, after embedding a contact material 24 in the openings H4 and H4′, an interlayer dielectric film 25 is formed on the interlayer dielectric film 14. As the contact material 24, for example, conductor, such as Al and Cu, can be used. Then, upper layer wires 26 connected to the lower layer wires 13 via the contact material 24 are embedded in the interlayer dielectric film 25.
In the above embodiment, the method is explained in which the sidewall patterns 27 are formed on the sidewalls of the openings H1 and H1′ for forming the openings H4 and H4′, however, the openings H4 and H4′ having a width smaller than the openings H1 and H1′ may be formed by adjusting the processing conditions.
Fifth Embodiment
FIG. 17A to FIG. 17F are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to the fifth embodiment.
In FIG. 17A, core patterns 32 are formed on a processing target layer 38 by using a method such as ArF immersion exposure. A plurality of the core patterns 32 having a linear shape is formed in parallel in an orthogonal direction with respect to the wiring direction DH in such a way as to be offset back and forth in three stages by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. The wiring pitch PH can be made to correspond to a minimum pitch of a line and space in a semiconductor integrated circuit. At this time, the width of the core patterns 32 can be set to 2 PH. Moreover, the interval between the core patterns 32 can be set to 2 PH. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the core patterns 32. The processing target layer 38 may be a semiconductor substrate, a dielectric layer formed on the semiconductor substrate, or the like, and is not specifically limited.
Next, as shown in FIG. 17B, the core patterns 32 are slimmed by a method, such as isotropic etching, to thin the line width of the core patterns 32. Then, sidewall patterns 33 are formed on the sidewalls of the core pattern 32. At this time, the sidewall pattern 33 has an internal offset by the amount of the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Next, as shown in FIG. 17C, the core patterns 32 are removed from over the processing target layer 38 while leaving the sidewall patterns 33 on the processing target layer 38.
Next, as shown in FIG. 17D, for example, a sidewall material is deposited on the whole surface of the processing target layer 38 including the sidewalls of the sidewall patterns 33 by a method, such as the CVD. Then, the processing target layer 38 is exposed while leaving the sidewall material on the sidewalls of the sidewall patterns 33 by performing anisotropic etching on the sidewall material, thereby forming sidewall patterns 34 on the sidewalls of the sidewall patterns 33. At this time, the sidewall pattern 34 has an internal offset by the amount of the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. Then, the sidewall patterns 34 facing each other with a space therebetween are brought into contact with each other at the stepped portions thereof, thereby forming openings H12 and H12′ surrounded by the sidewall patterns 34. At this time, the openings H12 and H12′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings H12′ of the first row are offset from the openings H12 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. The material of the sidewall patterns 34 may be the same as or different from the material of the sidewall patterns 33.
Next, as shown in FIG. 17E, mask patterns 35 that cover the spaces of both end portions of the sidewall patterns 34 are formed on the processing target layer 38 by using the photolithography technology and the etching technology. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the mask patterns 35.
Then, openings 36 and 36′ formed by transferring the openings H12 and H12′ are formed in the processing target layer 38 by etching the processing target layer 38 via the openings H12 and H12′. At this time, the openings 36 and 36′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings 36′ of the first row are offset from the openings 36 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Then, as shown in FIG. 17F, the sidewall patterns 33 and 34 and the mask patterns 35 are removed from over the processing target layer 38 in which the openings 36 and 36′ are formed. Thus, wires arranged in parallel at the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH can be formed on the openings 36 and 36′ along the wiring direction DH. The width of the wires can be set to ½ of the wiring pitch PH.
The openings H12 and H12′ partitioned by the sidewall patterns 33 and 34 are formed, therefore, the layout of the openings 36 and 36′ can be set without depending on the positioning accuracy in photolithography. Thus, even when the wiring pitch PH is set equal to or less than the resolution of the lithography, the contacts can be formed in the wires while suppressing an increase in area of the contact region.
Sixth Embodiment
FIG. 18A to FIG. 18F are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to the sixth embodiment.
In FIG. 18A, core patterns 42 are formed on a processing target layer 48 by using a method such as ArF immersion exposure. A plurality of the core patterns 42 having a linear shape is formed in parallel in an orthogonal direction with respect to the wiring direction DH in such a way as to be offset in a stepwise manner in three stages by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. The wiring pitch PH can be made to correspond to a minimum pitch of a line and space in a semiconductor integrated circuit. At this time, the width of the core pattern 42 can be set to 2 PH. Moreover, the interval between the core patterns 42 can be set to 2 PH. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the core patterns 42. The processing target layer 48 may be a semiconductor substrate, a dielectric layer formed on the semiconductor substrate, or the like, and is not specifically limited.
Next, as shown in FIG. 18B, the core patterns 42 are slimmed by a method, such as isotropic etching, to thin the line width of the core patterns 42. Then, sidewall patterns 43 are formed on the sidewalls of the core patterns 42. At this time, the sidewall pattern 43 has an internal offset by the amount of the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Next, as shown in FIG. 18C, the core patterns 42 are removed from over the processing target layer 48 while leaving the sidewall patterns 43 on the processing target layer 48.
Next, as shown in FIG. 18D, sidewall patterns 44 are formed on the sidewalls of the sidewall patterns 43. At this time, the sidewall pattern 44 has an internal offset by the amount of the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. Then, the sidewall patterns 44 facing each other with a space therebetween are brought into contact with each other at the stepped portions thereof, thereby forming openings H13 and H13′ surrounded by the sidewall patterns 44. At this time, the openings H13 and H13′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings H13′ of the first row are offset from the openings H13 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. The material of the sidewall patterns 44 may be the same as or different from the material of the sidewall patterns 43.
Next, as shown in FIG. 18E, mask patterns 45 that cover part of the spaces of both end portions of the sidewall patterns 44 are formed on the processing target layer 48 by using the photolithography technology and the etching technology. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the mask patterns 45. Then, openings 46 and 46′ formed by transferring the openings H13 and H13′ are formed in the processing target layer 48 by etching the processing target layer 48 via the openings H13 and H13′.
Then, as shown in FIG. 18F, the sidewall patterns 43 and 44 and the mask patterns 45 are removed from over the processing target layer 48 in which the openings 46 and 46′ are formed.
The openings H13 and H13′ partitioned by the sidewall patterns 43 and 44 are formed, therefore, the layout of the openings 46 and 46′ can be set without depending on the positioning accuracy in photolithography. Thus, even when the wiring pitch PH is set equal to or less than the resolution of the lithography, the contacts can be formed in the wires while suppressing an increase in area of the contact region.
Seventh Embodiment
FIG. 19A to FIG. 19D and FIG. 20A to FIG. 20D are plan views illustrating a manufacturing method of a contact region of a semiconductor device according to the seventh embodiment.
In FIG. 19A, mask patterns 51 are formed on a reticle 57. A plurality of the mask patterns 51 having a linear shape is formed in parallel in an orthogonal direction with respect to the wiring direction DH in such a way as to be offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. The wiring pitch PH can be made to correspond to a minimum pitch of a line and space in a semiconductor integrated circuit. At this time, the width of the mask patterns 51 can be set to 4 PH. Moreover, the interval between the mask patterns 51 can be set to 4 PH.
Then, as shown in FIG. 19B, core patterns 52 onto which the mask patterns 51 are transferred are formed on a processing target layer 58 by using a method such as ArF immersion exposure. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the core patterns 52. The processing target layer 58 may be a semiconductor substrate, a dielectric layer formed on the semiconductor substrate, or the like, and is not specifically limited.
Next, as shown in FIG. 19C, the core patterns 52 are slimmed by a method, such as isotropic etching, to thin the line width of the core patterns 52. Then, sidewall patterns 53 are formed on the sidewalls of the core patterns 52. At this time, the sidewall pattern 53 is offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. A material having a higher selectivity than the core patterns 52 can be selected as the material for the sidewall patterns 53. For example, when the core pattern 52 is formed of a BSG film, a silicon nitride film can be used as the sidewall patterns 53.
Next, as shown in FIG. 19D, the core patterns 52 are removed from over the processing target layer 58 while leaving the sidewall patterns 53 on the processing target layer 58.
Next, as shown in FIG. 20A, sidewall patterns 54 are formed on the sidewalls of the sidewall patterns 53. At this time, the sidewall pattern 54 is offset in the middle by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. A material having a higher selectivity than the sidewall patterns 53 can be selected as the material for the sidewall patterns 54. For example, when the sidewall pattern 53 is formed of a silicon nitride film, a polycrystalline silicon film can be used as the sidewall pattern 54.
Next, as shown in FIG. 20B, the sidewall patterns 53 are removed from over the processing target layer 58 while leaving the sidewall patterns 54 on the processing target layer 58.
Next, as shown in FIG. 20C, mask patterns 55 that cover part of the spaces between the sidewall patterns 54 are formed on the processing target layer 58 by using the photolithography technology and the etching technology, thereby forming openings H14 and H14′ surrounded by the sidewall patterns 54 and the mask patterns 55. At this time, the openings H14 and H14′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings H14′ of the first row are offset from the openings H14 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH. A resist material or a hard mask material, such as a BSG film and a silicon nitride film, may be used as the material for the mask patterns 55.
Then, openings 56 and 56′ formed by transferring the openings H14 and H14′ are formed in the processing target layer 58 by etching the processing target layer 58 via the openings H14 and H14′. At this time, the openings 56 and 56′ can be arranged in two rows in an orthogonal direction with respect to the wiring direction DH. Moreover, the openings 56′ of the first row are offset from the openings 56 of the second row by the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH.
Then, as shown in FIG. 20D, the sidewall patterns 54 and the mask patterns 55 are removed from over the processing target layer 58 in which the openings 56 and 56′ are formed. Thus, wires arranged in parallel at the wiring pitch PH in an orthogonal direction with respect to the wiring direction DH can be formed on the openings 56 and 56′ along the wiring direction DH. The width of the wires can be set to ½ of the wiring pitch PH.
The openings 56 and 56′ are formed in the regions partitioned by the sidewall patterns 54, therefore, even when the wiring pitch PH is set equal to or less than the resolution of the lithography, the contacts can be formed in the wires by arranging the openings 56 and 56′ in two rows.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Patent Application
20150008584
